ICD-10-CM > S00-T88 > T36-T50 > T40 > T40.4 > T40.41 > T40.414 T40.414 Poisoning by fentanyl or fentanyl analogs, undetermined Non-Billable/Non-Specific Codes T40.414A..., initial encounterT40.414D..., subsequent encounterT40.414S..., sequela